The present invention relates to an antenna device for a high-frequency radio apparatus, plus a high-frequency radio apparatus and a wrist watch-type high-frequency radio apparatus in which this antenna device is installed. The present invention specifically relates to an antenna device which is utilized for a very small radio apparatus such as a wrist watch-type apparatus.
A helical dipole antenna has been commonly utilized as an antenna for a high-frequency radio apparatus such as a cellular phone.
A helical dipole antenna is designed to be either extended from or kept within the portable device case when in use.
Furthermore, as disclosed in Japanese Patent Application Laid-Open Publication No.3-175826, there is another type of antenna, an inverted-F antenna, which, when installed within a portable device case, forms a diversity with a helical dipole antenna when utilized for a high-frequency radio apparatus.
Also, a chip antenna which is made out of a ceramic material has been utilized for a thin portable apparatus of the 2.4 [GHz] band card type.
However, a helical dipole antenna as described above is still too big for an apparatus which is desired to be more compact such as a watch-size portable apparatus. Therefore, it is difficult to simply install the helical dipole antenna within a small portable apparatus case.
Also, there is little flexibility in the formation of the inverted-F antenna since the antenna element and the ground plate (main plate) are formed as integral units. Consequently, making the inverted-F antenna compact is difficult.
On the other hand, with regard to the ceramic chip antenna, the chip antenna itself can be surface-mounted, yet it is still too big to be utilized as an antenna part with a surrounding circuit. In addition, the chip antenna is costly.
Furthermore, high flexibility of antenna configuration is desired if a small radio apparatus such as a cellular phone is to be made even more compact or its external design is to be improved by taking maximum advantage of the curve.
An object of the present invention therefore is to provide a compact antenna device for a high-frequency radio apparatus, plus a high-frequency radio apparatus and a watch-shaped radio apparatus in which the antenna is installed.
The antenna device for a high-frequency radio apparatus is characterized by an antenna element placed on a circuit board whose peripheral shape has a curve, the antenna element following the peripheral shape of the circuit board to have a curved part when viewed from above, and a ground pattern on which the antenna element touches.
In this case, the ground pattern can be placed on the board surface at a constant distance from the antenna element. Also, the ground pattern can be formed on almost the entire area of the circuit board other than where the antenna element is formed.
Also, the circuit board can be a multilayer circuit board, and the ground pattern can be formed on almost the entire area of any one internal layer of the multilayer circuit board other than where the antenna element is formed.
Also, the extending direction of the antenna element near the connecting point of the element and the tangential direction of the ground pattern""s connecting point can be more or less at right angles at the connecting point where the element is connected with the ground pattern.
Furthermore, assuming that the curved part is almost an arc when it is seen from above, the angle between the line which passes through the center of the circle, part of which forms the arc, and the connecting point where the antenna element touches the ground pattern and the straight line which passes through the tip of the antenna element and the circle center can be equal to or smaller than 180 degrees.
Also, the antenna device for a high-frequency radio apparatus is characterized by being equipped with a multilayer circuit board, an antenna element which is placed on the multilayer circuit board and a ground pattern the antenna element touches which is formed on almost the entire area of any one internal layer of the multilayer circuit board other than that on which the antenna element is formed.
Also, the antenna for a high-frequency radio apparatus is characterized by being equipped with a multilayer circuit board, an antenna element which is placed on the multilayer circuit board, a first ground pattern which is placed at a constant distance from the antenna element on the multilayer circuit board and is connected with the antenna element, and a second ground pattern which is formed throughout almost the entire area other than where the antenna element is formed within any one internal layer of the multilayer circuit board and is electrically connected with the first ground pattern.
In this case, the antenna element is the inverted-F antenna, and the element length can be approximately a quarter wave length of the designated radio frequencies.
Also, a high frequency radio apparatus is characterized by being equipped with an antenna part for a high frequency radio apparatus having an antenna element which is placed on a circuit board whose peripheral shape has a curve, the antenna element following the peripheral shape of the circuit board to have a curved part when viewed from above, and a ground pattern where the antenna element touches, and a radio communication part where radio communication takes place via the antenna for the high frequency radio apparatus.
In this case, the ground pattern can be placed at a constant distance from the antenna element toward the board surface.
Also, the ground pattern can be formed on almost the entire area of the circuit board other than where the antenna element is formed.
Furthermore, the circuit board can be a multilayer board, and the ground pattern can be formed on almost the entire area of any one layer of the multilayer circuit board other than where the antenna element is formed.
Also, a high frequency radio apparatus is characterized by being equipped with an antenna part for the high frequency radio apparatus comprising a multilayer circuit board, an antenna element which is placed on the multilayer circuit board, and a ground pattern where the antenna element touches which is formed on almost the entire area of any one layer of the multilayer circuit board other than where the antenna element is formed, and a radio communication part where radio communication takes place through the antenna part for the high frequency radio apparatus.
In this case, the radio communication part is equipped with a plurality of elements including a power supply, and among these plural elements, those which affect characteristics of the antenna part for the high frequency radio apparatus by being placed near the antenna part for the high frequency radio apparatus, can be placed on the circuit board by utilizing the ground pattern as the projecting plane and letting the orthogonal projection of the peripheral configuration of these elements fit in the projecting plane when elements are viewed from above.
Also, a high frequency radio apparatus is characterized by being equipped with an antenna part for a high frequency radio apparatus which contains a multilayer circuit board, an antenna element which is formed on the multilayer circuit board, a first ground pattern which is placed at a constant distance from the antenna element on the multilayer circuit board toward the board and is connected with the antenna element, and a second ground pattern which is electrically connected with the first ground pattern and is formed on almost the entire area of any one layer of the multilayer circuit board other than where the antenna element is formed, and a radio communication part where radio communication takes place through the antenna for the high frequency radio apparatus.
In this case, the radio communication part is equipped with plural elements including a power supply, and those plural elements which affect characteristics of the antenna for the high frequency radio apparatus due to their proximity to the antenna can be placed on the circuit board by utilizing the second ground pattern as the projecting plane and letting the orthogonal projection of the peripheral configuration of elements fit in the projecting plane when elements are viewed from above.
Also, a wrist watch-type high frequency radio apparatus is characterized by being equipped with an antenna part for the high frequency radio apparatus with an antenna element placed on a circuit board along the peripheral configuration of the circuit board whose peripheral configuration contains some curves when it is viewed from above along with a ground pattern where the antenna element touches, a radio communication part by which radio communication takes place through the antenna part for the high frequency radio apparatus and a wrist watch-type case in which the antenna part for the high frequency radio apparatus and the radio communication part are stored.
In this case, the ground pattern can be placed at a constant distance from the antenna element toward the board.
Also, the ground pattern can be formed on almost the entire area of the circuit board other than where the antenna element is formed.
Furthermore, the circuit board can be a multilayer circuit board, and the ground pattern can be formed on almost the entire area of any one layer of the multilayer circuit board other than where the antenna element is formed.
Also, a wrist watch-type high frequency radio apparatus is characterized by being equipped with an antenna part for the high frequency radio apparatus having a multilayer circuit board, an antenna element which is placed on the multilayer circuit board, and a ground pattern which is formed on almost the entire area of any one layer of the multilayer circuit board other than where the antenna element is formed, a radio communication part where radio communication takes place through the antenna for the high frequency radio apparatus, and a wrist watch-type case in which the antenna for the high frequency radio apparatus and the radio communication part are stored.
In this case, the radio communication part is equipped with plural elements including a power supply, and those elements among these plural elements which affect characteristics of the antenna part for the high frequency radio apparatus due to their proximity to the antenna part for the high frequency radio apparatus, can be placed on the circuit board by utilizing the ground pattern as the projecting plane and letting the orthogonal projection of peripheral configuration of these elements fit in the projecting plane when elements are viewed from above.
Also, a wrist watch-type radio apparatus is characterized by being equipped with an antenna part for the high frequency radio apparatus having a multilayer circuit board, an antenna element which is formed on the multilayer circuit board, a first ground pattern which the antenna element touches and is placed on the multilayer circuit board at a constant distance from the antenna element toward the board, and a second ground pattern which is electrically connected with the first ground pattern and is formed on almost the entire area of any one internal layer of the multilayer circuit board other than where the antenna element is formed, a radio communication part where radio communication takes place through the antenna for the high frequency radio apparatus, and a wrist watch-type case in which the antenna for the high frequency radio apparatus and the radio communication part are stored.
In this case, the radio communication part is equipped with plural elements including a power supply, and those elements which affect characteristics of the antenna part for the high frequency radio apparatus due to their proximity to the antenna part for the high frequency radio apparatus, they can be placed on the circuit board by utilizing the second ground pattern as the projecting plane and letting the orthogonal projection of peripheral configuration of these elements fit in the projecting plane when the elements are viewed from above.